The issue has aroused passions not seen in the profession for decades, but union predictions that 25,000 teachers would descend on central London this week fell some way short of expectations.

Instead, an estimated 1,000 teachers attended a mass lobby of Parliament on Wednesday (26 October) over the pension changes planned by the Government.

It was organised by seven unions, including those for teachers - the NUT, NASUWT and ATL - and headteachers’ organisations the NAHT and the ASCL, and saw teachers arrive at Westminster in the afternoon in an attempt to press their case with their local MP.

When details of the mass lobby were first publicised in September, teaching unions said “up to 25,000 teachers and lecturers” would make the trip.

This week, unions played down the reduced numbers and pointed to the 155,000-strong petition handed to the Department for Education as the true indicator of the strength of feeling over teachers’ working ages being extended and higher pensions contributions.

NUT deputy general secretary Kevin Courtney admitted the prospect of a national strike at the end of next month had probably suppressed numbers.

“I think the lobby has been overtaken by the 30 November decision, which came after the 25,000 number was issued,” he said. “The lobby is still an astonishing event, but a lot of the activists are focusing their attention on 30 November.”

Mr Courtney said the issue had united the teaching unions like never before. “What is different is the uniformity of this. In the 1980s, the ATL wasn’t involved; neither was the NAHT.”

A spokeswoman for the ATL, which held the first strike in its 127-year history on the issue at the end of June, said the mass lobby was in part to get public opinion on their side. “It’s also about getting in to see MPs. Things get refined like all plans.”

Among the teachers who did make it was Paula Roe, an English teacher at Redhill School in Stourbridge. Speaking to TES before her visit to London, she said she was hoping to see Stourbridge’s Conservative MP Margot James - who also happens to be a governor of Redhill.

Mrs Roe, an NASUWT member, said she would be more than pound;100 worse off because of the changes. “We’re being cheated out of a pension that we’ve paid in to. There is a mood of anger and disgust that the Government is doing this. I think the mood of teachers is that they will want to do more,” she said.

And former ATL president Julia Neal, who teaches history at Torquay Grammar School for Girls, said: “Nobody wants to go on strike, but if that’s what it takes that’s what we will do.”

She told her local MP, Liberal Democrat Adrian Sanders, that she would be around pound;130 worse off every month. “We’re being made to pay for the mistakes of the financial sector. We’ve been really hard done by,” she added.

Teachers may in part be cheered to find they have an unlikely ally for their cause. The head of education at Policy Exchange, which has been described as David Cameron’s favourite think-tank, said he had sympathy for teachers.

“It’s clear there’s a lot of resentment out there for what the financial services sector did,” said James Groves. “Teachers in the public sector are not on massive salaries; they work hard and I can understand them being irked.”

But he warned that long-term reform of public-sector pensions was inevitable. “We can’t avoid the fact that we have to have reform of public-sector pensions.”

COURT CHALLENGE

On Tuesday, the NASUWT was one of six unions challenging in the High Court a decision by the Government to align public-sector pensions with the consumer price index (CPI) rather than the retail price index (RPI).

The unions, including Unite and Unison, claim the move, announced in the 2010 Budget, could end up cutting the value of public-sector pension schemes by as much as 20 per cent.

The policy came into effect in April this year, when RPI (as of September 2010, the benchmark month) was 4.6 per cent, compared with the CPI rate of 3.1 per cent. Next year, pensions will rise by last month’s CPI rate of 5.2 per cent, compared with the RPI rate of 5.6 per cent.

The CPI rate excludes housing costs, which the Treasury said is a more appropriate measure of inflation.

The central plank of the unions’ case is that the Government has abused the 1992 Social Security Administration Act, claiming that the law does not exist for the purpose of cutting a national spending deficit.

A decision is due next month.

Original headline: Predicted pensions army of 25,000 falls short by 24,000